Some effects of chemical irritants on the membrane of the giant amoeba.
1 The effects of chemical irritants on the membrane potential and input resistance of the giant amoeba, Chaos carolinense, have been investigated. The membrane potential and input resistance were -111.5 mV and 8.6 M pi respectively. 2 In the resting state the cell membrane of Chaos carolinense was found to be impermeable to Na+ but permeable to K+. The distribution of K+ across the cell membrane conformed to a Donnan equilibrium with the resting membrane potential being the K+ equilibrium potential. 3 The chemical irritants dibenzoxazepine and its 2-chloro- and 3-chloro-analogues and o-chlorobenzylidene malononitrile produced a fall in input resistance but no change in membrane potential. It is suggested that these effects are caused by an increase in K+ permeability. 4 The potencies of a series of chemical irritants with respect to dibenzoxazepine were measured on the giant amoeba. These potencies did not reflect those found in mammalian preparations.
D000656:Amoeba / Q000187:drug effects*; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D003989:Dibenzoxazepines / Q000494:pharmacology; D007509:Irritants / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects*; D011188:Potassium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D009763:o-Chlorobenzylidenemalonitrile / Q000494:pharmacology
D003989:Dibenzoxazepines; D007509:Irritants; D009763:o-Chlorobenzylidenemalonitrile; D012965:Sodium Chloride; D011188:Potassium; D002211:Capsaicin